As I understand it, only factory installed options were shown on the window sticker. If this is the case, then any dealer installed options were accounted for seperately - on some documentation other than the factory window sticker.

My question is this, was it normal for the dealer to post any additional documentation adjacent to the factory window sticker to show the dealer installed options? If so, I'd be interested in knowing what form(s) was used and what it look like

Having bought a few cars in those days in my experience dealers did not 'pack' cars like they do today. If a buyer wanted an accessory it was added before delivery and noted on the sales contract. If a vinyl roof or something had been added it was noted on a slip of paper and pasted near the factory label.

One notable exception were Yenkos cars. The factory Chevrolet window labels were removed and replaced with SYC labels with their pricing.